AP Biology > Unit 5 > Flashcards

Unit 5 Flashcards

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1
Q

Define Genetics:

A

The study of heredity and hereditary variation.

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2
Q

Define heredity:

A

The transmission of traits from one
generation to the next

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3
Q

Define genes:

A

Segments of DNA that code for basic units of heredity.

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4
Q

How do offspring acquire genes from their parents?

A

Chromosomes

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5
Q

Identify asexual reproduction:

A

Requires 1 individual, creates clones through mitosis, and variation only caused by mutation.

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6
Q

Identify sexual reproduction:

A

Requires 2 parents, unique combination of parents, and genetically varied from parents and siblings.

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7
Q

Define homologous chromosomes:

A

A pair of identical chromosomes that carry the same genetic info

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8
Q

Define karyotypes:

A

A display of chromosome pairs ordered
by size and length

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9
Q

Define autosomes:

A

Chromosomes that do not determine sex

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10
Q

Define sex chromosomes:

A
  • X and Y chromosomes
  • Eggs have X and sperm have either X or Y
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11
Q

Define meisosis:

A

Haploid cells are generated from sexually reproducing diploid organisms.
- 2n -> n

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12
Q

Differences between mitosis and meiosis:

A

Mitosis occurs in somatic cells and creates 2 identical daughter cells
Meiosis forms gametes, has 2 divisions, and creates 4 unique haploid daughter cells.

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13
Q

What are the 3 key events of Meiosis:

A
  1. Prophase I
  2. Metaphase I
  3. Anaphase I
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14
Q

What happens in Meiosis interphase?

A

Cell goes through G1, S, and G2

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15
Q

How many divisions does meiosis have?

A

2 divisions

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16
Q

What happens in prophase I?

A
  • Homologous chromosomes condense and pair up through synapse
  • Meiotic spindle begins to form
  • Centrosomes move to opposite poles of the cell
  • Nuclear envelope breaks down
  • DNA is exchanged between non-sister chromatids via recombination
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17
Q

How are homologous pairs (tetrads) tied together?

A

Through a framework of proteins called a synaptonemal complex.

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18
Q

Where does recombination/crossing over occur?

A

On X-shaped connections called chiasmata

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19
Q

Prophase I produces:

A

Unique recombinant chromatids

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20
Q

What happens in Metaphase I?

A

Tetrads are aligned at the metaphase plate by meiotic spindle fibers.

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21
Q

What happens in Anaphase I?

A

Pairs of homologous chromosomes are pulled to poles by meiotic spindle fibers
- Sister chromatids are not separated yet

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22
Q

What happens in Telophase I and Cytokinesis?

A
  • Nuclear envelope forms
  • Cleavage furrow or cell plate forms
  • Cytokinesis forms and a haploid set of chromosomes are in each daughter cell
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23
Q

What happens in Prophase II?

A

No crossing over and attached sister chromatids attach to meiotic spindle

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24
Q

What happens in Metaphase II?

A

Chromosomes line up and each chromatid is unique

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25
What happens in Anaphase II?
Sister chromatids separate and move towards opposite poles
26
What happens in Telophase II and Cytokinesis?
Same key events but chromatids start decompressing and 4 genetically unique haploid cells are formed.
27
How can meiosis lead to genetic variation?
Crossing over, independent assortment during Metaphase, and random fertilization
28
What does meiosis followed by fertilization ensure and provide?
Genetic diversity and genetic variation in natural selection.
29
Meiosis requires the interaction of which components and uses what kind of energy?
Subcellular components / Free energy needed for growth and reproduction
30
Define nondisjunction:
When the homologous chromosomes or sister chromatids do not separate correctly and the following gametes are not haploid
31
Who is Gregor Mendel?
An Austrian monk who experimented on pea plants and discovered basic principles of heredity
32
What's P generation?
True-breeding parental generation
33
What is F1 generation?
Hybrid offspring of P generation (1st Filial)
34
What is F2 Generation?
Offspring of F1 generation (2nd Filial)
35
What are punnett squares?
Diagrams used to predict allele combinations
36
What does homozygous mean?
Organism with a pair of identical alleles (AA)
37
Heterozygous
An organism with 2 different alleles (Aa)
38
What's a genotype?
Genetic makeup (alleles) of an organism
39
What's a phenotype?
An organism's appearance, determined by genotype
40
What do testcrosses do?
Helps determine if dominant trait is homozygous dominant or heterozygous
41
What are the two principles of heredity?
1. The law of segregation 2. The law of independent assortment
42
What is the law of segregation?
The 2 alleles of the same trait separate during gamete formation and end up in different gametes.
43
What is the law of independent assortment?
Genes for one trait are not inherited with genes of another trait.
44
What are dihybrids?
F1 hybrids true breeding for 2 traits (YYRR x yyrr = YyRr)
45
What is a dihybrid cross?
A cross between F1 dihybrids (YyRr x YyRr)
46
What is the multiplication rule?
The probability that two or more independent events will occur together in some specific combination - Chance of heads landing twice on a coin (1/2 x 1/2 = 1/4)
47
What is the addition rule?
The probability that two or more mutually exclusive events will occur? - Dice rolling a 1 or 6 (1/6 +1/6 = 1/3)
48
What are pedigrees?
Family trees that give a visual inheritance patterns of particular traits
49
T/F: Dominant traits can skip a generation
False, if a trait is dominant, 1 parent must have the trait
50
What does it mean when a trait is X-linked?
Males are more commonly affected than females.
51
Why do many traits not follow Mendelian laws?
- Varying degrees of dominance - Multiple genes acting together - Some traits determined by sex chromosomes - Adjacent or close genes will segregate as a unit - Non-nuclear inheritance
52
Define complete dominance:
Homozygous dominant and heterozygous individuals are phenotypically the same
53
Define incomplete dominance:
Neither allele is fully dominant (F1 generation has mixed phenotype of parental generation) - Red and white flower make pink flower
54
Define codominance:
Two alleles that affect phenotype are both expressed - Red and white flower make red and white flower
55
Define multiple alleles:
Genes that exist in forms with more than 2 alleles
56
Define epistasis:
The phenotypic expression of a gene at one locus affects a gene at another locus
57
Define polygenic inheritance:
The effect of two or more genes acting on a single phenotype
58
Define pleiotropy:
When 1 gene controls multiple traits typically in multiple body systems (Marfan Syndrome) - They will not segregate independently
59
Define sex-linked genes:
A gene located on either the x or y chromosome
60
What's the difference between an X-linked gene and a Y-linked gene?
Y-linked genes are specifically found on Y chromosome and X-linked genes are specifically found on X chromosome
61
T/F: Fathers can pass X-linked alleles to all of their offspring
FALSE: Fathers cannot pass X-linked alleles to their sons
62
T/F: Mothers can pass X-linked alleles to all of their offspring
TRUE
63
When can females express an X-linked trait from a recessive allele?
If they are homozygous
64
Why will males express the trait if it's inherited from their mother?
Because they only have 1 X-chromosomes (Hemizygous) - Males are more likely to have an X-linked disorder
65
Define a Barr body:
Inactive X chromosome in each cell of a female condensed to help regulate gene dosage
66
Define linked genes:
Genes on same chromosome tend that tend to be inherited together
67
Define genetic recombination:
Production of offspring with a new combination of alleles from parents
68
Define parental types:
Offspring with the same phenotype as the parents
69
Define recombinants:
Offspring with new allele combination than parents
70
Linked genes show parental types in offspring at higher than __%
50%
71
The further apart 2 genes are on the same chromosome, __________.
The higher the probability that a crossing over event will occur between them and higher recombination frequency (50% max)
72
Define linkage map:
Genetic map that is based on recombination frequencies
73
Define map units:
Distance between genes - 1 map unit = 1% recombination frequency
74
What does 50% recombination mean?
Genes are far apart on same chromosome or 2 different chromosomes
75
Some traits are located on DNA found in the ___________ or __________.
Mitochondria / chloroplasts
76
In animals, mitochondrial DNA is ________ inherited
Maternally
77
In plants, mitochondrial and chloroplast determined traits are _________ inherited
Maternally
78
Define phenotypic plasticity:
Individuals with same genotype exhibit different phenotypes in different environments
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